Validation and application use cases

The techniques developed will be implemented in open source modules, integrated in larger CFD packages, including Nek5000, Nektar++, NS3D and SBLI and verified using real-world problems provided by the academic and industrial partners. The test cases used for validation include:

McLaren front wing.We use the representative geometry of a three component front wing with a complex end plate and representative wheel geometry at an experimental Reynolds number. The geometry has been investigated experimentally as a PhD project at Imperial College London, which therefore provides benchmark data. The test case contains complex geometry and ground effect, while also being representative of the aerodynamics found in many other applications such as the open flap and slat geometry of a wing during landing and take off.

NACA 4412 airfoil.This family of analytically defined airfoils is a standard test case within CFD; mainly with low-order code or RANS methods. The case is based on a twodimensional geometry, with periodic boundary conditions applied in the spanwise direction, which typically have an extent of 10-20% of the chord. Looking toward exascale computing (and further) the challenge is to run this sort of test case at Reynolds numbers of O(106-107), with different approaches including DNS, LES with resolved near-wall layers and LES with wall models (including heterogeneous models as discussed in the proposal). Note that resolved DNS of such a case will require about 10-100 billion grid points. The adaptive mesh strategy will thus be of particular importance in the turbulent wake of the airfoil where little information about the flow is known. The proposed simulations will be compared with planned experiments in the KTH wind tunnel at comparable Reynolds numbers.

Jet in Crossflow.This generic flow case of high practical relevance is obtained when a fluid jet through the wall enters a boundary layer flow along a wall. As its understanding is important in many real applications, this flow has been the subject of a number of experimental and numerical studies over the last decades. On the other hand this flow case with moderately complicated geometry and complex, fully three-dimensional dynamics provides a perfect tool for testing numerical algorithms and tools. Its benefit for testing the feature detection and I/O reduction strategies is that it contains a variety of length scales due to boundary layer turbulence, flow instability and breakdown of the jet. We are going to consider a circular pipe perpendicular to the flat plate.

Industrial use cases from the automotive sector.We select representative use cases from different phases of a vehicle design process: conceptual design, preliminary and detailed design, and product validation. Therefore geometry data is provides through the OEM members of the ASCS. In close cooperation with the OEMs relevant CFD problems will be defined. Moreover the focus is on comparison of problem solving with state-of-the art commercial CFD software tools in automotive industry and the new open source exascale techniques in this project.